EDIT: I will say that "I don't find this funny" is a valid point in -J feedback, because while normal SCPs can go for any sort of feeling, -Js have one that they have to achieve to be a success. And, while it's always better to explain why you don't find something funny, you often can't, because comedy is difficult to quantifiably dissect.

That said, linking to a YouTube video is a very smarmy and dismissive way of making that point. It's also not funny either.

Why?
"This isn't funny" is a perfectly legit way to shoot down a poorly made -J.

Furthermore, it's a lesser evil to posting nothing , because then, it looks like nobody's read the draft, or only one-two people who bothered to write half a fucking book about it. And thing there is, criticism is pretty often subjective, so dismissing it in some such cases is pretty often perfectly justified - if there's a lot, even short posts, it demonstrates it's the prevalent opinion. Which is something downvotes do when something is posted on-site.